The present invention relates to a collar forming apparatus for forming a collar or neck around an opening in a tube or a plate. Collar forming apparatus of this type is operable to work the metal surrounding an opening in the wall of a tube or a plate to flare the edge of the metal surrounding the opening outwardly and increase the size of the opening until an outwardly projecting collar or neck is formed around the enlarged opening. The collar forms a support to which a branch tube is affixed.
A composite hole forming and collar forming apparatus is described in U.S. Pat. No. 3,592,038 issued on July 13, 197l. The drilling and collar forming device disclosed in this patent employs at least two flange forming tools mounted on a drill and movable from retracted positions into extended positions displaced from the lateral surface of the drill wherein the end portions of the flange forming tools underlie the edge of the wall of the tube surrounding the opening. The forming tools then are rotated as the device is withdrawn from the hole to work the metal surrounding the opening to form an upstanding flange around the opening. A branch pipe then can be secured to the collar to be in communication with the main pipe. Forming an integral collar around an opening in the wall of the tube is advantageous because it eliminates the costly and difficult procedure of attaching T-fittings to the main tube. In addition, the structural integrity of the connection is ensured because the collar is an integral extension of the main tube.
Although the drilling and collar forming apparatus disclosed in U.S. Pat. No. 3,592,038 performs remarkably well, there are some limitations which are eliminated by the present invention. Because the flange forming tools are arranged in the drill disclosed in U.S. Pat. No. 3,592, 038 in a criss-cross manner, there are limits on the sizes of the openings around which a collar can be formed. Additionally, the forming tools disclosed in this patent have a cylindrical configuration and thus are not suitable for forming collars in tubes having a wide variety of wall thicknesses and varying material compositions. Finally, the drilling and collar forming apparatus disclosed in this patent is not capable of accepting flange forming tools of different sizes.
It is the general object of this invention, therefore, to provide a collar forming apparatus which is readily adapted to form collars around openings in tubes or plates having a variety of wall thicknesses and material compositions.
It is another object of the present invention to provide a collar forming apparatus having an improved mode of extending and retracting flange forming members.
It is another object of the present invention to provide a collar forming apparatus having flange forming members of improved design.